the Dexa machine on the bottom,

骨密度仪在最下面
the top left is measuring body fat with skin folds,

左上角是利用皮肤皱褶
through skin folds,

测量体内脂肪
and there is a device called skin fold calipers

有一种仪器叫做皮肤皱褶卡尺
that you see a researcher there using on a part of the back there

你看到一个研究人员用这种卡尺测量背部
where a pinch of body fat is made,

人为提起来的皮肤褶皱
the thickness of it is measured with the calipers.

卡尺可以测量这个皱褶的厚度
That's done on several places in the body,

在全身多处测量
and then you can use equations to figure out from that,

再代入公式演算
estimate from that how much body fat a person actually has.

从而估算一个人的体内脂肪含量
The most precise way, the gold standard of measuring this,

最精确的方法金标准
is to weigh people under water

就是检测水下体重